Hydrogen as electron donor for copper removal in bioelectrochemical systems

• Biological hydrogen oxidation was successfully combined with copper reduction.
• Open circuit voltage was close to theoretical voltage of the cell.
• Power density of 0.25 W/m2 was achieved at 0.48 A/m2.
• Hydrogen solubility was limiting the rate of the process.

Hydrogen gas is an attractive alternative electron donor since it is produced in large quantities as a side product in the metallurgical industry. Aim of this study was to demonstrate that microbial anodic hydrogen oxidation on a non-catalyzed graphite electrode can be coupled with cathodic copper reduction in a BES to simultaneously recover copper and produce power. The strategy was to first grow an anodic biofilm on acetate, then replace the acetate with hydrogen as electron donor, and finally combine hydrogen oxidation with copper reduction in the cathode. The maximum current density was 1.8 A/m2 at −250 mV anode potential vs Ag/AgCl. When coupled with Cu2+ reduction, the maximum power density was 0.25 W/m2 at a current density of 0.48 A/m2. Anode overpotentials were higher compared to acetate oxidation, probably a result of limited hydrogen solubility and transfer.

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